

A153340


Number of zigzag paths from top to bottom of a rectangle of width 8 with n rows.


1



8, 14, 26, 48, 90, 168, 316, 592, 1114, 2090, 3932, 7382, 13884, 26076, 49032, 92110, 173170, 325360, 611618, 1149248, 2160212, 4059360, 7629882, 14338290, 26949004, 50644750, 95185300, 178883252, 336200648, 631835054, 1187485194, 2231705808
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OFFSET

1,1


COMMENTS

Number of words of length n using an 8 symbol alphabet where neighboring letters are neighbors in the alphabet.  Andrew Howroyd, Apr 17 2017


LINKS

Table of n, a(n) for n=1..32.
Joseph Myers, BMO 20082009 Round 1 Problem 1Generalisation
Index entries for linear recurrences with constant coefficients, signature (1,3,2,1).


FORMULA

G.f.: 2*x*(4+3*x6*x^22*x^3)/((1x)*(13*x^2x^3)). [Colin Barker, May 10 2012]


MATHEMATICA

LinearRecurrence[{1, 3, 2, 1}, {8, 14, 26, 48}, 32] (* JeanFrançois Alcover, Oct 08 2017 *)


CROSSREFS

Column 8 of A220062.
Twice A090992.
Sequence in context: A226756 A029631 A187062 * A144842 A273843 A227867
Adjacent sequences: A153337 A153338 A153339 * A153341 A153342 A153343


KEYWORD

easy,nonn


AUTHOR

Joseph Myers, Dec 24 2008


STATUS

approved



